The present invention relates to an optical pick-up device and an optical component for the optical pick-up device suitable for recording information to and/or reproducing information from an optical disc based on a predetermined standard. In particular, the present invention relates to an optical component configured by forming an undercoating and a functional thin film on a base material, and to an optical pick-up device on which the optical component is mounted.
There exist various standards of optical discs, such as CD (Compact Disc), DVD (Digital Versatile Disc) and BD (Blu-ray Disc), differing in recording density, protective layer thickness, etc. An optical pick-up device on which an optical component, such as an objective lens or a collimator lens, is mounted is used to irradiate an information recording layer of an optical disc with a laser beam, and thereby to record information to and/or reproduce information from the optical disc.
There is a case where, when the information recording or information reproducing is performed by the optical pick-up device, unwanted reflected light or scattered light caused on optical surfaces of the optical pick-up device interferes with signal light, and thereby deteriorates a signal to be recorded or to be reproduced. Therefore, in many cases, a functional thin film, such as an antireflection coating or an antistatic film for preventing adhesion of dust, is provided on an optical surface of the optical component.
When assembling the optical pick-up device, dust or a finger mark adhered to the surface of the optical component is wiped out with a solvent. Accordingly, the functional thin film (e.g., an antireflection coating) is required to have abrasion resistance and chemical resistance as well as adhesiveness to the base material. Japanese Patent Provisional Publication No. HEI 6-273601A (hereafter, referred to as patent document 1) discloses technique in which a thin film formed with silicon oxide as a major component to have a predetermined film thickness is used as undercoating of an antireflection coating. Japanese Patent Provisional Publication No. 2006-228285A (hereafter, referred to as patent document 2) discloses technique in which thin films having silicon oxide as a major component and having different refractive indexes are alternately laminated to enhance the light resistance, and the laminated thin films are used as undercoating of the antireflection coating.